A special exchange program brings a Benzite named Mendon aboard the U.S.S. Enterprise and gives Riker the opportunity to become the first Federation officer to serve on board a Klingon ship.

Riker's preparations for his assignment include a lesson from Lt. Worf about Klingons, who still maintain the barbaric view that brute strength rules. The lesson is put to immediate use on board the Klingon cruiser Pagh when First Officer Riker must overpower the Second Officer when he questions Riker's authority and loyalty.

Meanwhile, the U.S.S. Enterprise discovers that a virulent strain of bacteria is eating away at the hulls of both their ship and the Klingon vessel. As the Enterprise plots a course to intercept and warn the Pagh, the Klingons discover the bacteria and mistakenly believe the starship is responsible for it. Unable to communicate with the cloaked Pagh, the U.S.S. Enterprise becomes concerned and raises its shields, which the Klingons immediately interpret as an act of aggression.

As the Pagh prepares to attack the U.S.S. Enterprise, Riker produces and activates an emergency transponder supplied to him by Worf prior to his transfer. The captain of the Pagh seizes the device and is soon beamed aboard the U.S.S. Enterprise. Now captain of the Pagh, Riker demands the surrender of Picard and the crew, allowing the Klingons to maintain their honor as warriors.

A short time later, the Enterprise aids in removing the bacteria from the Klingon ship and beams the Pagh's captain back to his vessel. Riker immediately surrenders his authority to the Klingon captain and returns to his duties on board the U.S.S. Enterprise.